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Journal Article

Mechanism of peptide-induced mast cell degranulation: translocation and patch clamp studies.

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Lindau,  M.
Research Group of Nanoscale Cell Biology, MPI for Biophysical Chemistry, Max Planck Society;

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Citation

Lorenz, D., Wiesner, B., Zipper, J., Winkler, A., Krause, E., Beyermann, M., et al. (1998). Mechanism of peptide-induced mast cell degranulation: translocation and patch clamp studies. Journal of General Physiology, 112(5), 577-591. doi:10.1085/jgp.112.5.577.


Cite as: https://hdl.handle.net/11858/00-001M-0000-0027-BF96-C
Abstract
Substance P and other polycationic peptides are thought to stimulate mast cell degranulation via direct activation of G proteins. We investigated the ability of extracellularly applied substance P to translocate into mast cells and the ability of intracellularly applied substance P to stimulate degranulation. In addition, we studied by reverse transcription--PCR whether substance P-specific receptors are present in the mast cell membrane. To study translocation, a biologically active and enzymatically stable fluorescent analogue of substance P was synthesized. A rapid, substance P receptor- and energy-independent uptake of this peptide into pertussis toxin-treated and -untreated mast cells was demonstrated using confocal laser scanning microscopy. The peptide was shown to localize preferentially on or inside the mast cell granules using electron microscopic autoradiography with 125I-labeled all-D substance P and 3H-labeled substance P. Cell membrane capacitance measurements using the patch-clamp technique demonstrated that intracellularly applied substance P induced calcium transients and activated mast cell exocytosis with a time delay that depended on peptide concentration (delay of 100-500 s at concentrations of substance P from 50 to 5 microM). Degranulation in response to intracellularly applied substance P was inhibited by GDPbetaS and pertussis toxin, suggesting that substance P acts via G protein activation. These results support the recently proposed model of a receptor-independent mechanism of peptide-induced mast cell degranulation, which assumes a direct interaction of peptides with G protein alpha subunits subsequent to their translocation across the plasma membrane.